Device for delivering under relatively diminished pressure gaseous products of combustion at high pressures of self-combustible solid fuels



Patented Mar. 2, 1954 VDEVICE Fon DELIVERING UNDER RELA-'rfvELYgDIMINIsnED PREssURE GAsEoUs VPnonUc'rs toti` coMBU's'rioN A'rHIGH rnEssUREs oF sELr-coMBUsTfBLE 'SOLID FUELS Edward Whitworth, VWestKnbriae,seonandasvsignor tolmperial Chemical Industries Limited,

a corporation of Great Britain Application May 4,1950,-Serial'No.159;988

Claims priority; application Great Britain July 25, 1949 =3 Claims. 1

The present invention is concerned with a'new and 'improved form' ofdevice'for enabling'pressure gases generated in a combustion'chamber bythe combustion of a self-combustible solid fuel, 'especially one based'ona single or'double 'base 'gelatinised nitrocellulose composition, topass' into another chamber under reduced'pressure; and comprisin'g apressure 'reducin'g'throat member guarded by 'a'filter'member adapted tor'etain parti'cles'of the'sol'd'self-c'ombustible fuel, an'd thuspreventthem from choking the or'ifice of'the throat'member.

In generating power gases for the operation of mechanical devices or for`rocket 'propulsion by the combustion of self-combustible 'solid' fuelssuch as for instance gelatinised nitrocellulose compositons, it is oftenfound that the combustion of lthe solid fuel will only take placesatisfactorily at a pressure substantially higher than that at which itis desired to utilise the power gases, and for'this purpose it iscustomary to provide a communication from the combustion chamber into anexpansion chamber'through a pressure reducing throat member,-which mustbe guarded against choking by fragments of the* solid fuel by a filterusually of gridlike' construction adapted to retain particles ofsolidffuel of -any considerable magnitudev projected againstit. It isalso customary to provide an emergency pressure release means throughthe wall of 'the 'combustion 'chamber to the exterior, consisting Iof adisc ladapted to burst at a predetermined pressure in excess of thepressure normally used for the combustion of the fuel, the external wallof the combustion chamber being modified so that a normally gas-tightseating can be provided for this safety disc. While a safety disc sopositioned is eifective in preventing the disruption of the combustionchamber should an excessive pressure develop within the latter owing toany interference with the discharge of the power gases therefrom, thebursting of the safety disc and the emergence of the thereby releasedpower gases to the exterior might constitute a certain hazard of injuryand fire.

This hazard and the inconvenience of modifying the contour of the wallof the combustion chamber, are avoided by the provision of the improvedform of device according to the present invention for enabling thepressure gases generated in the combustion chamber to pass into thelower pressure chamber.

According to the present invention a pressure reducing device adaptedfor use in a combustion chamber which is so constructed that theforward'end of 'its walll can be' threaded to the'rear- 'ward'end of thewall of an expansion'chair'iber and can form'with said rearward endVa'seating for the'circumferential portion of -a'fiange comprises ametal 'flange adapted toburst-at=a predetermined pressure 'and'to beheld in said seating, a pressure 'reducing throatl member aifd a`filter' member, wherein said' fiange is inthefvicinity of the lowpressure end of 'saidi'throat member, wherein saidy filter' member is inposition to guard the other end of s'aidthroat'membr, and wherein saidfiange is'adapted to suiznx'irt the combinationv of said throat memberand'saidffllter member.

The present invention also includes an'assembly 'compri'sing' acombustion chamber'havingf'a threaded end portion, an `exp'ansion`chamber having a threaded end portion,v a'm'e'tal'fiange, a pressurereducing throat member, and-a 'filter member, wheren'said ohambersareadapted to be screwed together to form a seating'for'the'circumfere'ntial portion' of va `fian`ge, 4 whe'rei'n said flange isheld in said seating, is adaptedv t'o'burst at a predetermined pressureand is inthe'yicinity of the 'low-pressure end of said throat 'member,wherein said filter memberissin positin'A to gu'ard the other end ofsaid 'throat member, wherein 'said flang'e 'is adapted'tosupportfthe'combination of said throatmember andsaid'filter member, 'and where'insaid combinatio'n is positioned within said combustion chamber.

The pressure at which the fian'g'e'isfadapted to burst'is lower than'thepressure' at whi'ch*`the 'external wall of the combustion chamber 'wouldrupture, so that if by any chance the fiow of gases from the interior ofthe combustion chamber through the pressure reducing throat shouldbecome interrupted and a pressure greater than is desirable be built upin the combustion chamber, the resulting bursting of the fiange memberwill cause the discharge of the power gases to take place into the lowerpressure chamber instead of to the atmosphere outside and the need for abursting disc or other pressure release member to the exteror isavoided.

The filter member and the flange of metal that iS adapted to yield underthe said predetermined pressure may advantageously be formed as a unitfrom the same piece of metal, the pressure reducing throat member beingthreaded to the filter member in order to locate the latter in such aposition that all the gases passing the filter must pass through thethroat member. The flange however can otherwise be formed integral withthe pressure reducing throat member, the

aovdsoa filter in this case being threaded on to the throat A member.Alternatively the throat member and the filter member can each befianged and the throat member threaded in the filter member to form adouble layered fiange member.

If desired the circumferential portion of the flange of the aforesaiddevice can be held in the seating formed by the threading together ofthe combustion chamber and the expansion chamber with the assistance ofannular gaskets so as to improve the efificiency of the gas-tight joint.

The invention will be further understood by reference to thediagrammatic drawing accompanying the specification, which represents anisometric view of a longitudinal axial section illustrating an improveddevice in accordance with the invention in Operating position betweenthe forward portion of a combustion chamber and the rearward portion ofa lower pressure chamber.

In the drawing l is the external wall of the combustion chamberexternally threaded as shown at IO. 2 is an internally threaded endportion of the wall of a lower pressure chamber, the shoulder loadinginto this threaded portion and the forward end of the Wall i beingaccurately cut so as to provide a seating for fiange li of the filtermember 3 with the aid of gasket rings 8 and 9. The filter member 3 isslotted on its cylindrioal and rearward end surfaces as shown at 5 for aportion of its length, the annular fange portion 4 being formedcontinuously with the latter of the same steel 5. The forward unsiottedportion of the wall of the filter member is internally threaded as shownat 6 and therein is screwed an externally threaded pressure reduoingthroat member 'I providing a throat through which the gases from thecombustion chamber pass into the other chamber at a reduced pressure. Itwill be understood that the pressure at which the annular ange 4 burstsis considerably below the safety limit of pressure for the wall l of thecombustion chamber.

I claim: i 1. In combnation, a combustion chamber for generatingcombustion gases, said combustion chamber having a gas outlet end, anexpansion chamber having an inlet end for receiving gases from theoutlet end of said combustion chamber, means connecting the inlet end ofsaid expansion chamber to the outlet end of said combustion chamber,said means forming a seat about the entire periphery of the connection,a pressure reducing throat member having a high pressure end Within saidcombustion chamber and a low pressure end opening into said expansionchamber permitting passage of gas from said combustion chamber into saidexpansion chamber at reduced pressure, a filter member positioned withinsaid combustion chamber to guard the high pressure end of said throatmember and a metallic fiange positioned about said throat member,adjacent the low pressure end thereof, and held in said seating to forma fluid-tight separating wall between said combustion chamber and saidexpansion chamber, said fiange being adapted to burst at a predeterminedpressure to permit gases within said combustion chamber to exit intosaid expansion chamber When said pressure is exceeded.

2. A pressure reducing device adapted for use in a combustion chamberwhich is so constructed that the forward end of its wall can be threadedto the rearward end of the wall of an expansion chamber and can formwith said rearward end a seating for the peripheral portion of a flange,said device comprising a pressure reducing throat member having a highpressure and a low pressure end, a filter member threaded onto said highpressure end of said throat member and having an exterior flangeportion, said fiange portion having a predetermined bursting pressurelower than the bursting pressure of the external wall of the cornbustionchamber and being held in said seating adjacent the low pressure end ofsaid throat member so that the filter member filters the gases generatedin the combustion chamber and passing through the said throat memberinto the said expansion chamber.

3. A device according to claim 2 wherein the filter member is in theform of a cylinder having its rearward end partially closed by a slottedportion, the slots in which are continued along a portion of the cylnderwall.

EDWARD WHITWORTH.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date V 1,983,330 Welch Dec. 4, 1934 2,062,381 Tryon et al. Dec. 1,1936 2,169,359 Jones et al. Aug. 15, 1939 2,195,925 Hoesel Apr. 2, 19402,342,996 Barker et al Feb. 29, 1944 2,400242 Malina et al. May 14, 19462,457,578 Maliphant Dec. 28, 1948

